Which of the following frequencies will be suitable for beyond-the-horizon communication using sky waves? a) 10 kHz b) 10 MHz c) 1 GHz d) 1000 GHz
(b) 10 MHz The signal waves must travel a long distance in order to communicate beyond the horizon. Because of the antenna size, 10 kHz transmissions cannot be broadcast effectively. The ionosphere is penetrated by high-energy signal waves (1GHz - 1000GHz). 10 MHz frequencies are easily reflected by the ionosphere. As a result, signal waves of such frequencies are acceptable for communication beyond the horizon.
